Capacitative commutator



CAPACITATIVE COMMUTATOR Filed July 15, 1946 3 Sheets-Sheet 1 INVENTOR. Cfzarasfllalzpfaer, fim, y 24m wQM I C. H. LANPHIER CAPACITATIVE COMMUTATOR :s Shets-Sheet 2 April 30, 1957 Filed July 15, 1946.

United States Patent O1 CAPACITATIVE COMMUTATOR Charles H. Lanphier, Springfield, 11]., assignor to Sangarno Electric Company, Springfield, Ill., a corporation of Illinois Application July 15, 1946, Serial No. 683,694

Claims. (Cl. 33324) The present invention relates to a czupacitative commutator or rotary switching device which performs commutative or rotary switching functions by relative motion between spaced capacitative surfaces rather than by physical contact between brushes and commutator segments or slip rings. This capacitative commutator or capaci-tative switching device has particular application to situations where the current flows relatively small, and possesses numerous advantages over the conventional arrangement of brushes in direct physical contact with commutator segments, slip rings, etc. For example, the commutation is smooth and continuous and free from the sudden shifts which attend the use of a brush and segment type of commutator; all sparking is eliminated with its consequent variations of resistance in the connected circuit; all brush wear is eliminated; vastly higher speeds are made practicable, etc.

One of the particular fields of utility for my improved capacitative commutator is in connection with under-water sound echo ranging systems for detecting underwater targets. One such type of underwater sound detection system, for which my invention has been particularly devised, is disclosed in the copending application of Oscar H. Schuck and Leon G. S. Wood, filed August 14, 1944, Serial No. 549,460, now Patent No. 2,697,822, December 21, 1954. In such a system, this capacitative commutator performs commutative or rotary switching functions between the transducer and the receiving apparatus, particularly between the transducer and the elements of the electrical network constituting the so-called lag line. The elements of this lag line network rotate directly with the rotary element of the capacitative commutator.

The. general object of the present invention is to provide a capacitative commutator which will be completely reliable under severe operating conditions, which will be compact, which will have a high degree of alignment accuracy of the various critical elements, particularly the capacitative elements, and which will enable ready checking and correction of the spacing between the rotating and stationary capacitative elements.

Other objects, advantages and features of the invention will appear from the following detail description of one preferred embodiment thereof. In the accompanying drawings illustrating such embodiment:

Figure 1 is a side view, mostly in axial section, of the capacitative commutator;

Figure 2 is an end view of the left hand end of the unit as viewed in Figure 1;

Figure 3 is a face view of the rotary cap-acitative disk, corresponding to a transverse sectional view taken on the plane of the line 3-3 of Figure 1 and looking in the direction indicated by the arrows;

Figure 4 is a fragmentary face view of the stationary capacitative disk, corresponding to a fragmentary transverse sectional view taken on the plane of the line 4--4 of Figure 1 and looking in the direction indicated by the arrows, and

Figure 5 is a detail sectional view showing the metallized linings which extend through the holes in the com mutator plates for establishing electrical connection with the commutator segments. p

The capaci-tative commutator elements are enclosed within a main house 10 comprising left and right cylindrical housing sections 11 and 12. These two housing sections are joined together by peripheral meeting flanges 1:3 and .14 which are adapted to be clamped together by the cap screws or bolts 15. Tapered dowel pins 16 carried by one of these flanges are adapted to be received within companion openings in the other flange, so as to compel angular registration of the flanges in the operation of bolting these two housing sections together. Disposed beyond the left hand end of the housing 10 is a transformer supporting ring 18. This ring supports a circularly arranged series of commutator input transformers 19 having mounting flanges 21 (Figure 2) which are secured to the front face of the supporting ring 18 by screws 22, the body portions of the transformers projecting longitudinally through openings in the supporting ring 18. The capacitative commutator herein disclosed has been designed particularly for use with a transducer of the con struction disclosed in my copending application Serial No. 683,695, filed July 15, 1946, on Transducer, now Patent No. 2,515,154, J-uly L1, 1950, in which construction there are 48 vertical columns or staves of magnetostrictive elements disposed around the circumference of the transducer. One of these commutator input transformers 19 is provided for each vertical column or stave of magnetostrictive elements, and accordingly there are 48 of these transformers I19 grouped around the supporting ring 18. The inner portion of the ring 1 8 is formed with a sloping inner web 24 in which are provided openings 25 for receiving sections of a cable 26 made up of a plurality of conductors, these conductors being adapted to have connection made with the primary windings of the transformers 19 on the back or inner :side of the supporting ring 18. The supporting ring 18 is detach-ably secured to the end wall of the circular housing section 11 by cap screws 28 which pass through a central hub 29 of the supporting ring and tap into threaded bores in the end wall of the housing section 11. The secondary windings of the transformers .19 have electrical connection with the capacitative segments of the stationary commutator plate, as I shall presently describe.

The housing section 11 is formed at its outer end with a bearing boss 31 in which are confined two thrust sustaining ball bearings 32, 32 which rotatably support the adjacent reduced end of a rotor shaft 33. These two thrust bearings 32 sustain all thrust load on the rotor shaft 33 in both directions. The outer races of said bearings are confined between a bearing retainer ring 35 and a bearing spacer ring 36 which abuts against a statorplate hub 37 The bearing retainer ring 35 is drawn up against the bearings by cap screws 38 which thread into the stator plate hub 37. The inner races of the thrust bearings are confined between a gap control spacing ring 41 and an adjusting or looking nut 42 which screws over a thread 43 on the reduced outer end of the rotor shaft 33. A removable cover plate 44, detachably secured to the retainer ring 35 by screws 45, afiords access to the retainer screws 38 and to the nut 42.

Bolted to a machined inner surface 47 in the housing section 11 is the commutator stator 48. This commutator stator is adapted to cooperate with the commutator rotor 49 revolving with shaft 33. Both of these commutator elements are in the form of circular disks of insulating material, preferably glass. The stator plate 48 is centrally mounted on the stator plate hub 37 and is bolted in stationary position by cap screws 51 which pass through openings in the end wall of housing section 11 and through lined or cushioned openings 52 in Patented Apr. 30, 1957 greases ring 53 set back into a recess in the front surface of the glass disk, which recess is faced by a cushioning ring 54. The rotor plate hub 56 is preferably shrunk upon an enlarged portion of the rotor shaft 33, although it may be fixedly secured thereto in any other suitable manner.

The opposing faces of the stationary disk 48 and of the rotating disk 49 are provided with capacitative segments 58 and 59 respectively (Figures 3 and 4) which perform the commutative function between these two disks. These commutator segments are preferably formed by coating or metallizing the opposing plane surfaces of these two disks with silver or other suitable metal, and then cutting narrow radial lines through this metal coating to divide the latter into the desired number of radial segments. Since this capacitative commutator is intended for use with the transducer disclosed in my aforementioned copending application, Serial No. 683,695, filed July 15, 1946, in which there are 48 vertical columns or staves of magnetostrictive elements, I preferably provide 48 stationary segments 58 on the stationary disk, and 48 rotating segments 59 on the rotating disk. An even ratio of stationary segments 58 and rotating segments 59 is not essential, and, in fact, some operating advantages may be obtained by employing a greater number of rotating segments than stationary segments, such as a 2 to 1 ratio; i. e. 48 stationary segments and 96 rotating segments. The opposing surfaces of these segments are accurately finished, and, in the typical construction shown, the air gap between the segments on one disk and the segments on the other is preferably adjusted and maintained at a value of approximately 0.0035 inch. However, it will be understood that the dimension of this gap g is merely exemplary, and may be made larger or smaller for different sizes of disks, different operating conditions, etc. In a machine of the general proportions shown, the cooperating pair of segments 58 and 59 each function as capacitors of approximately 100 mmfd, serving to establish circuit connections between the transformer 19 and the different portions of the electrical network or lag line which rotate with the rotating commutator disk 49. The segments 58 on the stationary disk 48 are electrically connected with the transformer 19 through holes 61 drilled through the disk 48, there being one of these holes for each segment 58. Each of these holes is metallized internally with silver or some other similar high conductivity metal, as indicated at 61' in Figure 5, the front end of the metallized sleeve thus formed being in direct electrical connection with its associated commutator segment 58. Forced into the rear end of this metallized hole 61 is a metallic bushing 62, and secured in the inner end of this bushing is a conducting rod 63. Each of these rods 63 extends rearwardly through an insulating bushing 64 mounted in the end wall 11 of the housing section 11. The outer end of the conducting rod 63 is connected through a flexible conducting strap 65 with one of the terminals of the secondary winding of the corresponding transformer 19. In the sectional view of Figure l the conducting hole 61 extending to the next adjacent segment 58 is illustrated in dotted lines, this being at a different radius than the hole illustrated in full lines. Thus, as clearly shown in Figure 4, the conducting holes for alternate segments occur alternately at inner and outer radii so that more space is afforded at the outer ends of the conducting rods 63 for establishing connection through the flexible straps 65 with the transformers 19. The rotating commutator segments 59 on the rotating disk 49 have an identical arrangement of metallized holes 61, conducting thimbles 62 and conducting rods 63. The outer ends of these conducting rods 63 have electrical connection through flexible conducting straps 65 with terminals 66 having connection with the elements of the rotating lag line. The terminals 66 are mounted in the rotating housing of the lag line assembly.

The lag line assembly is contained within a rotating housing 71 having the cross section of a U-shaped annulus. A bolting flange 72 extends inwardly from this housing and is secured to the rotating plate hub 56 by cap screws 73. The lag line comprises a network made up of series-connected inductances, parallel-connected capacitances and terminal impedances, all as set forth in the aforementioned copending application of Oscar H. Schuck and Leon G. S. Wood, Serial No. 549,460. A plurality of the rotating commutator segments 59 are connected with different points of this lag line through the conducting straps 65 and terminals 66. The various units of the lag line can be assembled into the U-shaped housing 71 through the open left hand end, which open end is then closed by a removable cover 75 secured to the housing by the screws 76.

Electrical take-off connections lead from the lag line to portions of the receiving apparatus through the instrumentality of three collector rings 77, 78 and 79 with which engage brushes fragmentarily indicated at 81. The collector ring assembly is keyed or otherwise secured to the shaft 33 in any suitable manner, and a collector ring washer 82 is interposed between this collector ring assembly and the adjacent end face of the rotor plate hub 56. Collector ring terminal anchors 83 on this washer establish electrical connection between three tapping points of 'the lag line and the three collector rings 77, 78 and 79. The brushes 81 are supported in a removable mounting bracket 85 which is secured by screws 86 to a radial wall 87 within the housing section 12. The brushes 81 have electrical connection through terminal posts 88, which are accessible from the outer side of the bracket 85, there being three of these terminal posts, one for each of the brushes. The rotor shaft 33 is formed with a reduced right hand end which has bearing support within a roller bearing 91. The outer race of bearing 91 is confined between bearing plate 92 and retainer flange 93, these being secured together by the screws 94. The inner race of the bearing is confined between a bearing plate 95 and the hub of a drive gear 96 mounted on the rotor shaft. The rollers of this bearing can slide endwise within the outer race, or the rotor shaft 33 can slide endwise within the inner race, or both, so that this roller bearing only sustains radial loads and does not restrict axial movement of the shaft. Thus, all thrust loads on the shaft are sustained by the thrust bearings 32 at the other end of the shaft, and all axial adjustments of the shaft for commutative disk spacing are performed at this left hand end. The drive gear 96 is keyed to shaft 33 and is held in place by a retainer nut 97 screwing over a thread 98 on the right hand end of the shaft.

Meshing with the gear 96 is a driving pinion 101 mounted on shaft 102 of an electrical driving motor 103. Said motor has an end flange 104 which is bolted to a mounting ring 105 secured by dowel pins 106 and cap screws 107 to the end of the housing section 12. The driving motor 103 is usually an induction motor.

Driven in synchronism with the rotating commutator disk 49 is a multiple phase generator 110, such as a three phase alternating current generator. This generator is secured by clamping screws 111 within a mounting boss 112 projecting outwardly from the mounting plate 105. The shaft 113 of this generator carries a gear 114 which meshes with the drive gear 96, whereby the rotor of the generator is constantly driven in synchronous relation to the rotary commutator plate 49. The generator 110 is surrounded by inner and outer shields 115 and 116 for preventing interference with other parts of the receiving apparatus. The three phase output of the generator 110 is utilized to obtain a spiral sweep trace in the oathode ray tube of the receiving apparatus, all as fully disclosed in the aforementioned copending application of Oscar H. Schuck and Leon G. S. Wood.

Attention is directed to the fact that the above described construction of capacitative commutator can be completely dis-assembled for repair or inspection and reassembled with the assurance that the exact alignment will be maintained, particularly in respect to the air gap 3 between the stationary glass plate 48 and rotating glass plate 49. Inspection hatches 121 are secured to the housing section 11 by screws 122, these inspection hatches covering inspection openings 123 through which observation can be made of the gap g between the stationary commutator disk 48 and the rotating commutator disk 49. Adjustments of this gap can be made by substituting different widths of gap control spacer ring 41.

In order to minimize any variations in capacitative coupling due to temperature changes, the rotor shaft 33 is preferably made of a low expansion alloy, and the arrangement of the various parts in such as to produce only minimum dimensional changes in the parts. All end play is taken up in the thrust bearing assembly 32, the rear roller bearing 91 permitting axial movement of the housing or of the rotor shaft with respect to each other without any binding, the function of this roller bearing being merely to preserve the radial accuracy of the rotor shaft alignment.

The other side of the primary circuits leading to the primary windings of all of the transformers 19 can be completed through a common conductor or ground, and the other side of the secondary circuits leading from the secondary windings of all of the transformers 19 can be completed through the frame of the machine or ground.

While I have illustrated and described what I regard to be the preferred embodiment of my invention, nevertheless it will be understood that such is merely exemplary and that numerous modifications and rearrangements can be made therein Without departing from the essence of the invention.

I claim:

1. In a capacitative commutator of the class described, the combination of a substantially cylindrical housing, a stationary commutator disk composed of insulating material disposed in said housing, a rotating commutator disk also composed of insulating material rotatably mounted in said housing in alignment with said stationary disk and spaced therefrom, an electric motor operatively connected to drive said rotating commutator disk, metallic coatings on the opposing faces of said two disks, spacing lines in said metallic coatings defining cooperative capacitative segments on said opposing faces, the number of capacitative segments on said rotating disk being at least equal to the number of capacitative segments on said stationary disk, holes extending through said disks from the opposing faces to the outer faces thereof, metallized linings in said holes establishing electrical connection with the commutator segments on said opposing faces of the disks, a supporting ring detachably mounted at one end of said housing for ready removal from the housing, a plurality of commutator input transformers mounted circularly around said supporting ring and adapted for removal with said ring as a unitary assembly, and electrical connectors extending from said transformers into said housing and connecting with the metallized linings of the holes in said stationary disk, said electrical connectors comprising readily separable portions which facilitate electrical disconnection between said transformers and said metallized linings when said supporting ring and transformers are removed as a unitary assembly.

2. In a capacitative commutator of the class described, the combination of a substantially cylindrical housing comprising an end wall, a rotating shaft journaled in said end wall, a stationary commutator disk composed of glass disposed axially of said shaft and adjacent said end wall, a rotating commutator disk also composed of glass mounted on said shaft in alignment with said stationary disk and spaced therefrom, an electric motor operatively connected to drive said rotating commutator disk through said shaft, metallic coatings upon the opposing faces of said two disks, spacing lines in said metallic coatings defining cooperative capacitative segments on said opposing faces, the number of capacitative segments on said rotating disk being at least equal to the number of capacitative segments on said stationary disk, holes extending through said disks from the opposing faces to the outer faces thereof, metallized linings in said holes establishing electrical connection with the commutator segments on said opposing faces of the disks, a supporting ring detachably mounted on the end wall of said housing for ready removal from the housing, a plurality of commutator input transformers mounted circularly around said supporting ring and adapted for ready removal with said ring as a complete unitary assembly, insulating bushings in said end wall, conducting thimbles seated in said metallized linings in the holes of said stationary disk, electrical connectors extending from said thimbles outwardly through said insulating bushings, and flexible conducting straps establishing readily separable electrical connection between said electrical connectors and said commutator input transformers enabling ready electrical disconnection to be made between said transformers and said electrical connectors when said supporting ring and transformers are removed as a unit.

3. In a capacitative commutator of the class described, the combination of a substantially cylindrical housing, end walls for said housing, a commutator shaft extending axially of said housing, thrust sustaining anti-friction bearings mounting one end of said shaft in one of said end walls, a radial load type of anti-friction bearing supporting the other end of said shaft in said other end wall, said thrust sustaining bearing carrying all of the thrust on said shaft, means cooperating with said thrust sustaining bearing for effecting axial shifting adjustments of said shaft, a stationary commutator disk composed of insulating material anchored to the end wall of said housing adjacent said thrust sustaining bearing, a rotating commutator disk also composed of insulating material mounted on said shaft in alignment with said stationary disk and spaced therefrom, capacitative commutator segments on the opposing faces of said disks, and an electric motor carried by said housing and having geared connection with said commutator shaft for driving said rotating commutator disk.

4. In a capacitative commutator of the class described, the combination of a housing having first and second axially spaced end walls, a commutator shaft journaled in said end walls, a thrust sustaining anti-friction bearing mounting one end of said shaft in said first end wall, a roller anti-friction bearing mounting the other end portion of said shaft in said second end wall, astationary commutator disk composed of insulating material disposed axially of said shaft and secured to said first end wall, a rotating commutator disk also composed of insulating material mounted on said shaft in alignment with said stationary disk and spaced therefrom, adjusting means cooperating with said thrust sustaining bearing for axially shifting said shaft to adjust the width of gap between the opposing faces of said two commutator disks, said roller anti-friction bearing accommodating such shifting movement of said shaft, metallic coatings on the opposing faces of said two disks, spacing lines in said metallic coatings defining cooperative capacitative segments on said opposing faces, the number of capacitative segments on said rotating disk being at least equal to the number of capacitative segments on said stationary disk, holes extending through said disks from the opposing faces to the outer faces thereof, metallized linings in said holes establishing electrical connection with the commutator segments on said opposing faces, and an electric motor operatively connected to drive said shaft.

5. In a capacitative commutator of the class described, the combination of a housing having first and second axially spaced end walls, a commutator shaft journaled in said end Walls, a thrust sustaining anti-friction bearing mounting one end of said shaft in said first end wall, a roller anti-friction bearing mounting the other end portion of said shaft in said second end wall, a stationary commutator disk composed of insulating material disposed axially of said shaft and secured to said first end wall, a rotating commutator disk also composed of insulating material mounted on said shaft in alignment with said stationary disk and spaced therefrom, adjusting means cooperating with said thrust sustaining bearing for axially shifting said shaft to adjust the width of gap between the opposing faces of said two commutator disks, said roller anti-friction bearing accommodating such shifting movement of said shaft, metallic coatings on the opposing faces of said two disks, spacing lines in said metallic coatings defining cooperative capacitative segments on References Cited in the file of this patent UNITED STATES PATENTS 1,671,143 Campbell May 29, 1928 1,913,512 Reynolds June 13, 1933 2,157,715 Meggenhofen May 9, 1939 2,186,268 Pakala Jan. 9, 1940 2,326,341 Ehlers et al Aug. 10, 1943 2,382,413 Hanert Aug. 14, 1945 FOREIGN PATENTS 700,998 Germany Jan. 6, 1941 

